Nowadays, attention is being paid to a technology that increases the resolution of an input moving image signal or still image signal and outputs the resulting signal. For example, if only the resolution of the moving image region can be increased in the display region, even a coarse input moving image can be displayed with improved viewability.
If such a moving image region is fixed, it can be identified manually. However, the identification process is troublesome. Of course, if the moving image region moves, there is a limit to identifying it manually.
There have been proposed various methods for identifying a moving image region. For example, Patent Document 1 discloses a method for determining a motion on a block basis. Specifically, the determination method includes: making a comparison between the gray levels of the same pixel in the preceding and following frames; if there is a difference between the gray levels, judging that the pixel is a moving-image pixel; obtaining the ratio of the number of the moving-image pixels to the number of all the pixels on a block basis; and if the ratio is greater than the threshold, judging that the block is a moving-image block.